Spring actuated feeding mechanism for use with
pushthrough-type cartridge links



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AM MMMQM Oct. 3, 1967 R-,H- COI-BY 3,344,712

SPRING ACTUATED FEEDING MECHANISM FOR USE WITH PUSHTHROUGH-TYPE CARTRIDGE LINKS Filed Sept. 14, 1961 4 Sheets-Sheet 4 IN VEN T 0R.

Rid-mmf H Bunny v United States Patent O The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to machine guns which are supplied with cartridges by means of a belt comprised of cartridge holding links and pertains more specifically yto the feeding mechanisms of such guns.

In modern ordnance there has been provided a cartridge which has a projectile with artillery capabilities yet which may be tired in shoulder-type firearms. However, diiculty is encountered in designing a machine gun for use with this special cartridge because the projectile has a fragile windshield which may be dangerously damaged if, as in conventional feeding mechanisms, the cartridge belt is fed into the gun receiver at one level and the cartridges, during transfer from the cartridge belt into the barrel chamber, are angularly deflected into alignment with the barrel axis at another level because such deflection is produced by impact of the cartridge projectile with a structural member of the gun during transfer.

The obvious solution to this design problem is to feed the cartridge belt into the gun receiver in line with the gun bore axis so that the gun bolt may push the cartridges linearly from the belt into the barrel chamber without striking the projectile against any gun structure during the transfer, and then replace the red case in the belt. However, with previous feeding mechanisms using the pushthrough-type link, which makes this linear transfer possible, all require long receivers because the belt, which cannot be displaced until after the fired case is repositioned therein, is actuated by overtravel of the bolt.

It is, therefore, one object of this invention to provide a machine gun for discharge of such cartridges with a feeding mechanism which transfers the cartridges linearly from the belt into the barrel chamber and vreplaces the fired cases in the belt but which does not require overtravel of the bolt for actuation, whereby the length of the machine gun receiver may be reduced to a minimum.

It is another object of this invention to `actuate such a feed mechanism by a spring which -is energized by the bolt during the recoiltravel thereof when replacing a fired case in the cartridge belt.

It is a further object of this invention to provide such a machine gun wherein the feeding mechanism, bolt and cartridge belt cooperate to produce aslow rate of fire' without the need for an added ratereducing device.

' It is still another object of this invention to provide for the discharge of such cartridges a machine gun which is compact in size, simple in construction, positive in operation and which lires at a slow rate without the need for a special rate reducing device.

The specic nature of thel invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

FIG. 1 is a longitudinally cross-sectioned view of the machine gun shown in battery;

FIG. 2 is a view taken along line 2-2 of FIG. l;

FIG. 3 is a fragmentary view similar to FIG. l but 3,344,712 Patented Oct. 3, 1967 showing the relationship of the parts during recoil movement of the bolt;

FIG. 4 is a fragmentary view similar to FIG. 3 but showing the bolt latched in the recoil position and the cam plate released from the bolt;

FIG. 5 is a view similar to FIG. 3 but showing the cam slide in the forward position and the latch actuated thereby to release the bolt;

FIG. 6 is a view taken along line 6-6 of FIG. 1;

FIG. 7 is a view taken along 7--7 of FIG. 2; and

FIG. 8 is a perspective, exploded view of the bolt, cam slide, latch, latch release and spring assembly members.

Shown in the figures is a machine gun 12 which is supplied with cartridges 14 by means of a belt 16 composed of a plurality of cartridge holding links 18 which are each provided with a bolt actuated latch for holding the engaged cartridge against longitudinal displacement relative thereto. Link 18 is more fully disclosed in inventors copending application for a Pushthrough-type Cartridge Belt Link with Bolt Actuated Cartridge Retaining Latch, Ser. No. 123,906, dated July 13, 1961, now Patent No. 3,152,512. Cartridges 14 are each provided with a projectile 21 having artillery capabilities so as to be best fired at a slow rate and a case 22 having an annular groove 24 positioned therearound adjacent the base to form an extractor rim 26.

Gun 12 includes a rectangular receiver 28 which is open at the top and such opening is closed by a cover 29 hinged to the receiver at the front end. A barrel 30 is mounted in the front end of receiver 28 and a bolt 32 is mounted in the receiver for sliding reciprocation in axial alignment with the barrel between a battery and a recoil position. A buffer device 34 is positioned in the rear end of receiver 28 and is disposed to resiliently stop bolt 32 in the recoil position. Bolt 32 is biased forwardly to the battery position by a spring 35.

Bolt 32 includes a breechblock 36 which is dimensioned to pass through link 18 and which is provided along the bottom with an integral flange 38 of inverted T-conguration in cross-section. Flange 38 is received by a mating slot 40 in the bottom of receiver 28 for slidingly mounting bolt 32 therein. A longitudinal mouth 41 is provided along the bottom of each link 18 to receive flange 38 during passage of breechblock 36 through the link. Formed in the front end of breechblock 36 is a lateral T-slot 42 which is arranged to matingly receive the rear end of case 22 and engage extractor groove 24. Thus, when engaged with bolt 32, cartridge 14 is pushed through associated link 18, during travel of the bolt from the recoil to the battery position, and fired case 22 is repositioned in the same link during travel of the bolt to the recoil position. A firing pin 43 is slidingly mounted in breechblock 36 and is biased to a retracted position therein by a spring 45.

Belt 164is moved laterally through receiver 28 in a feedway 44 by means of a pair of rails 46 which are xed to the ceiling thereof and which are of inverted T-conguration in cross-section. Rails 46 are receivable by a pair of mating slots 48 in the top of each of the links 18 and are arranged ,to guide the links in belt 16 so that extractor grooves 24 of cartridges 14 therein are slidingly received by T-slot 42 and the links are delivered successively to a stripping position in receiver 28. When in such stripping position, cartridges 14 in the links 18 are disposed in longitudinal alignment With the bore of barrel 30 and close to the breech end thereof to permit direct displacement into the barrel chamber.

Belt 16 is progressively moved along feedway 44 by a feeding mechanism 51 which includes a cam plate 52. Such cam plate 52 is mounted in cover 29 for sliding longitudinal reciprocation therein between a forward and a rearward position parallel to the path of movement of bolt 32 when the cover is closed and includes `a cam groove 54. Also mounted in cover 29 is a spring assembly 56 which is received by a longitudinal channel 58 formed longtitudinally in the `cover above cam plate 52. Spring assembly 56 includes a tube 59 which is closable at both ends and in such tube there is received a compressible coil spring 60 and a piston 61 which is slidable in the tube and which has `contact with the front end of the spring. A pin 62 xes piston 61 to cam plate 52 and extends through a longitudinal opening 64 in tube 59 so that the cam plate is biased by spring 60 to the forward position thereof in cover 29 and rearward displacement of the cam plate loads the spring. Cam plate 52 is connectable to bolt 32, as hereinafter described, so as to be displaced rearwardly during travel thereof to the recoil position and then is released from the bolt for return to the forward position through the lbias of spring 60 leaving the bolt seared in the recoil position.

A feed slide 66 is mounted in feedway 44 between rails 46 and is arranged to be slidingly supported thereby. A cam follower 68 extends upwardly from feed slide 66 to be received by cam groove 54 in cam plate 52, when cover 29 is closed, and such cam groove is generated to translate longitudinal reciprocation of the cam plate to lateral displacement of the feed slide a distance slightly greater than the pitch distance between links 18 in belt 16. Cam groove 54 is also generated so that when cam plate 52 is -displaced rearwardly by bolt 32, feed slide 66 is -actuated from left to right in feedway 44 in a retracted stroke. Feed slide 66 is actuated from rig-ht to left in a feeding stroke bythe energy in spring 60 when cam plate 52 is actuated forwardly thereby.

Feed slide 66 carries a feed pawl 70 which is pivotally mounted thereon and arranged to depend therefrom. Feed pawl 70 is spring-biased downwardly to contact links 18 when in feedway 44 and is arranged to transfer displacement of feed slide 66 during displacement thereof in the feeding stroke to the link which is next in belt 16 after the one indexed in the stripping position and to pass over the next successive link in the belt during the following retracted stroke.

A pair of holding pawls 72 `are pivotally mounted on the ceiling of feedway 44 at the left end thereof so that each of the holding pawls is disposed between one of the rails 46 and the adjacent side of feedway 44. Holding pawls 72 are spring-biased downwardly and arranged to engage links 18 after passing thereby to prevent reverse displacement of belt 16.

A stop pawl 74 is pivotally mounted on the ceiling of feedway 44 at the right end thereof and is arranged to extend langularly downwardly and to the left so that the end contacts link 18 when in the stripping position to oooperate with feed pawl 70 contacting the link on the opposite side in indexing the link so that breech-block 36 may readily enter thereinto. Stop pawl 74 extends through an opening 76 in feed slide 66 and is springbiased upwardly to a position free from interference with belt 16. An edge 78 forming the left side of opening 76 is arranged to cam stop pawl 74 downwardly into position to engage link 18 when moved into stripping position by feed p'awl 70 and to free the stop pawl for upward displacement clear of belt 16 during displacement of feed slide 66 in the retracted stroke.

Cam plate 52 is connected to bolt 32 during recoil travel by a catch 80 which is essentially of inverted U- shape in cross-section and which is mounted in. the bolt in a mating clearance 82 and so as to be displaceable in `a vertical plane. Catch 80 includes a lateral cross-piece 84 provided with a cam surface 86, which extends angularly upward and rearward from the front -face of the crosspiece to the top thereof, and a pair of laterally spaced legs 88 which depend from the cross-piece. A pin 90 is inserted transversely through bolt 32 so as to be received by a vertical slot 92 in each of the legs 88 and such slots are formed to limit vertical displacement of catch between an upward engaging position wherein cam surace 86 extends above bolt 3-2 and a depressed unlatched position. A pair of springs `94 act respectively against the bottom vof each of the legs 88 for biasing catch 80l to the engaging position. Catch 80 is `actuated to the unlatching position by a pair of cooperating lugs 96 which respectively extend inwardly from the sides Iof receiver 28 to be engageable by a pair of shoulders 98 formed respectively on the outside of each of the legs 88. Shoulders 98 each extend upwardly and forwardly from the rear end of catch 80 so that when the shoulders contact legs 98 longitudinal movement of the catch with bolt 32 during recoil travel thereof is converted to vertical displacement of the catch to the unlatch position. Lugs 96 'are positioned t-o contact shoulders 98 for disconnecting cam plate 52 from bolt 32 when the bolt is adj'acent the recoil position thereof. Cam plate 52 is lconnected to bolt 32 through the contact of the rear end of cross-piece 84 with rear side 100 of a slot 102 in the underside of the cam plate.

Bolt 32 is releasably held in the recoil position, after release of cam plate 52 therefrom, by a latch 104 pivotally mounted in the rear end of cover 29. Bolt 32 is held by latch 104 so that T-slot 42 is positioned to receive the rear end of cartridge 14 during displacement by belt 16 to the stripping position. Latch 104 is pivotally mounted on a transversal shaft 105 and is spring-biased downwardly respective to cover 29, when closed, to a bolt engaging position by a double-armed spring 106. When in the bolt engaging position, latch 104 has engagement with a hook projection 107 on the rear end of bolt 32 to releasably hold the bolt in the recoil position. A lug 108 with 'a cam surface 110 extends from the left side of latch 104 for cooperation with a latch release 112 slidingly disposed in cover 29 in a mating groove 114 on the left side of channel 58.

Latch release 112 includes a bar 116A which is terminated at the rear end by an L-shaped actuator 118 having a cam surface 120 which is disposed for contact with cam surface .and for cooperation therewith so that, when latch release 112 is displaced forwardly, latch 104 is 'actuated to bolt release position. Bar 116 extends forwardly to where the front end thereof overlaps slightly the rear end of cam plate 52 when the cam plate is in the forward position thereof. A pin 122 is mounted in the front end of bar 116 to depend vertically therefrom so that the end of the pin is slidingly received by a longitudinal channel 124 formed in the top surface of the cam plate 'and thereby permits movement thereof relative to latch release 112. Channel 124 is provided with a rear end 126 which is arranged to have conta-ct with pin 122 when cam plate 52 approaches the forward position thereof so that, during continued displacement thereof to the forward position, latch release 112 is actuated `for release of the bolt. A retainer 128 is mounted in the front end of groove 114 and a spring 130 is disposed therein between the retainer and the front end of bar 116 for biasing latch release 112 to the rearward position thereof to prevent any interference between lug 108 and actuator 118 land provide free displacement of latch 104 to the bolt engaging position When bolt 32 is in battery position, firing pin 43 is actuatable to discharge cartridge 14 chambered in barrel 30 by a hammer 132 which is pivotally mounted on the base of receiver 28. Hammer 132 is disposed in the path of bolt 32 during recoil travel thereof so as to be rammed downwardly thereby to a first-seared position and the hammer is releasably held in the first-seared position by an automatic sear 134 which is slidingly disposed in the base of receiver 28. Automatic sear 134 is arranged to be engaged by bolt 32 when adjacent battery position for release of hammer 132. A secondary sear 136 is disposed in the base of receiver 28 for actuation by a trigger 138 and to releasably hold hammer 132 in a second-seared position, after release from automatic sear 134, and when the trigger is in the normal forward position thereof. If trigger 138 remains held in the tiring position when hammer 132 is released by automatic sear 134, secondary sear 136 is positioned clear of the hammer so that the hammer is free to continue its pivotal displacement to strike firing pin 43.

Operation When machine gun 12 is ready to be fired, bolt 32 is in battery position with a cartridge 14 removed thereby from an associated link 18 and chambered in barrel 30, and harnmer 132 is held in the second-seared position by secondary sear 136. To re machine gun 12, trigger 138 is pulled displacing secondary sear 136 for release of hammer 132 which swings upwardly t-o strike firing pin 43 and thereby discharge the chambered cartridge 14.

Responsive to the discharge forces, bolt 32 is actuated by blowback of case 22 to the recoil position. As bolt 32 moves rearwardly, fired case 22 is repositioned thereby in ylink 18 from which it had previously been stripped and, through the engagement of catch 80 with cam plate 52, the cam plate is actuated rearwardly with the bolt. When bolt 32 approaches recoil position, shoulders 98 on catch 80 contact lugs 96 to cam the catch downwardly for disengagement from cam plate 52. Thus, cam plate 52 is free to return to the forward position through the bias of spring 60 which had been compressed during the rearward travel of the cam plate. Bolt 32 remains engaged in the recoil position by latch 104.

When cam plate 52 was traveling rearwardly with bolt 32, cam groove 54 moved relative to cam follower 68 to actuate feed slide 66 fr-om left to right and thereby moved feed pawl 70 over link 18 next subsequent to that indexed in the stripping position and released stop pawl 74 so as to be biased upwardly out of the way of the link in the stripping position. When cam plate 52 is released from bolt 32 by the disengagement of catch 80 from the cam plate, feed pawl 70 is positioned in back of the succeeding link 18 in belt 16 so that, during the forward travel of the cam plate when feed slide 66 is actuated from right t-o left in feedway 44, the feed pawl moves the link engaged thereby to the stripping position and so advances the belt one pitch. As feed pawl 70 moves to advance belt 16, stop pawl 74 is cammed downwardly to cooperate with the feed pawl in holding link 18 engaged therebetween in the stripping position.

When cam plate 52 reaches the forward position thereof, the feed pawl engaged link 18 is indexed in the stripping position and pin 122 in latch release 112 has been contacted by rear end 126 of channel 124 in the cam plate to displace the latch release for actuating latch 104 to release bolt 32. When released, bolt 32 goes forward to battery position pushing cartridge 14 in the index positioned link 18 therefrom into barrel 30.

During the recoil travel of bolt 32, hammer 132 was pivoted down thereby to be engaged in the first-seared position by automatic sear 134. When bolt 32 returns to battery position, automatic sear 134 is actuated by the bolt to release hammer 132. If trigger 138 has been released, hammer 132 will be reengaged by secondary sear 136 so as to be under the control of the trigger. However, if trigger 138 remains pulled, hammer 132 continues its pivotal displacement to strike firing pin 43 for discharge of cartridge 14 in barrel 30 to initiate another cycle.

The speed at which cam plate 52 returns to the forward position thereof and, therefore, the time interval between the latching of bolt 32 in the recoil position and the unlatching thereof by the cam plate when it reaches its forward position is determined by the difference between the energy transferable by spring 60 to the cam plate and the amount of energy required to displace cartridge belt 16. Thus, cartridge belt 16, in combination with feeding mechanism 51 and bolt 32, acts as a rate reducer which reduces the normal rate, which machine gun 12 would fire without any cartridge belt drag, to a slow rate without any added devices being introduced. 'e

From the foregoing it is readily apparent that there is taught herein a feeding mechanism which makes possible a compact and light machine gun with a short receiver and which has cooperation with the cartridge belt and the bolt for reducing the normal rate of re to a slow rate without the need for a special rate reducing device being introduced.

Although a parti-cular embodiment of the invention has been described in detail herein, it is evident that many variations may be devised within the spirit and scope thereof and the following claims are intended to include such variations.

I claim:

1. In combination, a machine gun and cartridge belt for supplying cartridges thereto for discharge, said machine gun being provided with a bolt disposed for cyclic reciprocation responsive to energy produced by discharge of each of the cartridges and a feeding mechanism adapted to progressively advance said cartridge belt through said machine gun, said feeding mechanism being provided with energizing means including a spring assembly having a compressible recoil spring and a slidable piston disposed in abutment therewith, means for transferring energy produced by cartridge discharge to said energizing means, said transfer means including a cam plate disposed for sliding reciprocation parallel to the reciprocation of said bolt means for transferring travel of said bolt in a recoil stroke to said cam plate and means for joining said cam plate to said piston for actuation therebetween against said spring, and means for interrupting the cyclic reciprocation of said bolt a period determined by the difference between the energy stored in said energizing means and that required to advance said cartridge belt.

2. The combination as defined in claim 1 wherein said means for interrupting the cyclic reciprocation of said bolt includes a latch arranged to releasably hold said bolt in a recoil position, a Icam plate disposed for longitudinal reciprocation between a forward and a rearward position parallel to the path of reciprocation of said bolt, means for transferring travel of said bolt in a recoil stroke to said cam plate, means for transferring the energy in said bolt through said cam plate to said energizing means, means for releasing said cam plate from said bolt when adjacent the recoil position to permit forward displacement of said cam plate by said energizing means, and release means operationally disposed between said feed slide and said latch for actuating said latch to release said bolt when said cam plate reaches the forward position thereof after release from said bolt.

3. In combination, a machine gun and a cartridge belt for supplying cartridges thereto for discharge, said cartridge belt being comprised of a plurality of cartridge engaging links adapted to permit the engaged cartridges to be pushed linearly therethrough and the fired case returned thereto, and said machine gun being provided with a bolt disposed for longitudinal reci-procation between a battery and a rec-oil position and adapted to push the cartridges through their engaging links during travel to the battery position and to return the red cases to the respective links during travel to the recoil position, and a feeding mechanism including means for interrupting cyclic reciprocation of said bolt at the recoil position, means for advancing said cartridge belt one pitch during the interruption of said bolt including a spring assembly disposed so as to be energizable by said bolt during displacement thereof to the recoil position, pawl means disposed for engagement with said cartridge belt for successively positioning the links therein in a stripping position, means for transferring the energy in said spring means to said pawl 4means for actuating said pawl means to advance said cartridge belt after said bolt is interrupted in the recoil position, and means for releasing said bolt for displacement to the battery position after said cartridge belt is advanced one pitch'by said pawl means.

4. The combination as defined in claim 3 wherein said feeding mechanism includes a cam plate disposed for sliding longitudinal displacement, catch means carried by said bolt for engagement with said cam plate for transferring displacement of said bolt to the recoil position to rearward displacement of said cam plate, a spring assembly disposed to be energized by said cam plate during rearward displacement thereof, a latch disposed for releasably holding said bolt in the recoil position, means for actuating said catch means when said bolt is adjacent the recoil position to release said carn plate from said bolt for forward displacement by said spring assembly, a feed slide mounted for sliding displacement transversal to the longitudinal axis of the machine gun, a feed pawl pivotally carried by said feed slide and arranged to be engageable with successive ones of said links during reciprocation of said feed slide for progressively advancing said cartridge belt in increments of one pitch, cooperating cam means on said cam plate and said feed slide for converting longitudinal displacement of said cam plate to transversal displacement of said feed slide, and means actuatable by said cam plate when in 8 the forward position thereof for actuating said latch to release said bolt.

5. The combination as defined in claim 4 wherein said feed slide is disposed for sliding reciprocation in a feedway and said feeding mechanism includes additionally a stop pawl pivotally mounted on said feedway and springbiased so as to be displaced free from interference with said cartridge belt, an opening in said feed slide to permit the extension of said stop pawl therethrough, and an edge .of said opening arranged to cam said stop pawl into position to contact said link when displaced to the stripping position opposite the engagement of said feed pawl therewith.

References Cited UNITED STATES PATENTS 1,040,692 10/1912 Kjellman 89--33 1,709,162 4/1929 Westervelt et al. 89--33.l5 2,504,994 4/ 1950 Lochhead 89-33 2,821,886 2/1958 Friend et al. 89-33.2

BENJAMIN A. BORCHELT, Primary Examiner.

W. E. STEWART, F. C. MATTERN, S. C. BENTLEY,

Assistant Examiners. 

1. IN COMBINATION, A MACHINE GUN AND CARTRIDGE BELT FOR SUPPLYING CARTRIDGES THERETO FOR DISCHARGE, SAID MACHINE GUN BEING PROVIDED WITH A BOLT DISPOSED FOR CYCLICRECIPROCATION RESPONSIVE TO ENERGY PRODUCED BY DISCHARGE OF EACH OF THE CARTRIDGES AND A FEEDING MECHANISM ADAPTED TO PROGRESSIVELY ADVANCE SAID CARTRIDGE BELT THROUGH SAID MACHINE GUN, SAID FEEDING MECHANISM BEING PROVIDED WITH ENERGIZING MEANS INCLUDING A SPRING ASSEMBLY HAVING A COMPRESSIBLE RECOIL SPRING AND A SLIDABLE PISTON DISPOSED IN ABUTMENT THEREWITH, MEANS FOR TRANSFERRING ENERGY PRODUCED BY CARTRIDGE DISCHARGE TO SAID ENERGIZING MEANS, SAID TRANSFER MEANS INCLUDING A CAM PLATE DISPOSED FOR SLIDING RECIPROCATION PARALLEL TO THE RECIPROCATION OF SAID BOLT MEANS FOR TRANSFERRING TRAVEL OF SAID BOLT IN A RECOIL STROKE TO SAID CAM PLATE AND MEANS FOR JOINING SAID CAM PLATE TO SAID PISTON FOR ACTUATION THEREBETWEEN AGAINST SAID SPRING, AND MEANS FOR INTERRUPTING THE CYCLIC RECIPROCATION OF SAID BOLT A PERIOD DETERMINED BY THE DIFFERENCE BETWEEN THE ENERGY STORED IN SAID ENERGIZING MEANS AND THAT REQUIRED TO ADVANCE SAID CARTRIDGE BELT. 